Universidad de Chile - Facultad de Medicina - Programa de Genética Humana - ICBM

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NOVEDADES EN LA RED

El Sida y los romanos: el imperio contrataca.

The Complete Works of Charles Darwin on-line

Recurso para estudiantes, investigadores y profesionales de la salud que trabajan en la interfase de Medicina y Evolución

Los sitios Darwin200 y Darwin 2009, A Festival, reúnen información relevante sobre las actividades que se llevarán a cabo en el Reino Unido con motivo del 200 aniversario del nacimiento de Charles Darwin

La obesidad: un problema que afecta a la mayor parte de la humanidad). Bajar artículo original en sección Artículos temáticos

Prof. E. Aspillaga (Sesión teórica "Patrones de evolución del linaje homínido") participa en excavación arqueológica de homínidos en el sitio Atapuerca, España

Recurso interactivo del BBC world service web site dedicado a los fundamentos de la biología del VIH. Introduction The HIV virus Infection Early stages Aids develops Anti-HIV drugs

https://www3.nationalgeographic.com/genographic/atlas.html. Atlas of the Human Journey /The NatGeo Genographic Project. Sitio con materiales interactivos para conocer el rol de las migraciones en la evolución de nuestra especie

http://www.ncbi.nlm.nih.gov/ Recurso valioso para Trabajo Personal. OMIM (On Line Mendelian Inheritance In Man) es un catalogo extensivo y actualizado de las enfermedades genéticas humanas, con abundantes links, sinopsis clínicas, susceptibilidades y genes específicos. Es accesible en el menú de la pagina principal de NCBI (el mismo de GenBank)

Reconstrucción digital aplicada a la medicina http://www.ifi.unizh.ch/staff/zolli/CAP/biomedical.htm

Visita el sitio de PBS para revisar materiales relacionados con la Unidad I de la asignatura

Visita el sitio http://www.aboutdarwin.com/index.html, donde encontrarás numerosos recursos y material de apoyo relacionados con la vida y obra de Charles Darwin y su rol en la formulación de la Teoría de la Evolución por Selección Natural

-Materiales publicados en la red sobre las consecuencias de la "carrera armamentista" y del abuso de antibióticos

The Antibiotic Resistance Project web site

Cost of evolution runs into billions

from NewScientist, London http://www.newscientist.com/

Humans are causing evolution on a grand scale - and it is costing us hundreds of billions of dollars each year, says a Harvard biologist. The sooner we realise it, he says, the sooner we can slow evolution down. Every time a strain of bacteria becomes resistant to an antibiotic, or a weed mutates so it can thrive after being sprayed with a herbicide, there is a financial cost to humankind, Stephen Palumbi points out. He estimates that cost to be at least $100 billion every year in the US alone. "And that's got to be an underestimate," Palumbi told New Scientist. "We are paying a lot for these arms races." Decision-makers need to anticipate evolution and build it into public policy, he says. Lord Robert May of the Royal Society, London agrees. "So many of the triumphialist claims that we can eradicate something like infectious disease could only be made by someone who didn't appreciate the moving nature of the target," he told New Scientist.

Last resort
Palumbi highlights several of the most costly results of human evolutionary pressure. The emergence of antibiotic-resistant strains of the bug Staphylococcus aureus, and the loss of crops due to herbicide and pesticide resistance are two key problems, he says.
But HIV is the fastest-evolving, says Palumbi. It evolves so quickly, it forms a new "quasi-species" inside every person it infects, he says. He thinks humans must implement strategies to slow evolution down as a matter of urgency.

Interspersing the use of one herbicide with another is one option. Another ploy is to withhold a powerful treatment as a last resort, to prevent resistance developing. Vancomycin, a powerful antibiotic, is now used as a treatment of last resort in many hospitals around the world. It is the only option for use against superbugs such as MRSA (methicillin-resistant S. aureus). But although the principles of strategies to slow evolution are well known, Palumbi believes that they have been re-invented from scratch several times. "If they realised that other people had blazed that trail, it might be far easier," he says. "In the US more than half the people don't believe in evolution. We have to train people about it - we can't afford not to."

by Andrea Graves. Palumbi's lab web site at Stanford University: http://www.stanford.edu/group/Palumbi/

 TEMAS DE LA ASIGNATURA RELACIONADOS CON ESTA NOTICIA:

Teoría de la selección natural. Leyes de Malthus. Selección natural y artificial (antibióticos), relajación. Teorías sintética y post-sintéticas.

Co-evolución. Enfermedades infecciosas como paradigma evolutivo. Enfermedades infecciosas emergentes

-Materiales sobre el problema del envejecimiento desde el punto de vista de la Medicina evolucionaria

Visista la sección especial dedicada al tema en el número de Science del 3 deSeptiembre de 2004 (http://www.sciencemag.org/sciext/aging2004/)

El envejecimiento en el macaco como modelo animal del envejecimiento humano 

Roth GS, JA Mattison, M Ottinger, ME Chachich, M Lane & DK Ingram1, 2004. Aging in Rhesus Monkeys: Relevance to Human Health Interventions Science 305: 1424-1426

TEMA DE LA ASIGNATURA RELACIONADO CON ESTE MATERIAL:

Objetivo transversal. Razones por las que un médico debe pensar en la evolución

Evolución biológica y cultural. Los nuevos ambientes y enfermedades de la civilización

-Materiales sobre la complejidad de las interacciones genotipo-ambiente y sus consecuencias para la salud humana

PD Gluckman & MA Hanson 2004. Living with the Past: Evolution, Development, and Patterns of Disease Science 305: 1733-36

TEMA DE LA ASIGNATURA RELACIONADO CON ESTE MATERIAL: Evolución biológica y cultural. Los nuevos ambientes y enfermedades de la civilización

 

Early hominid ears primed for speech 

(Baja la versión PDF del artículo original comentado en esta nota!)

12:19 22 June 04
NewScientist.com news service

Early humans evolved the anatomy needed to hear each other talk at least 350,000 years ago. This suggests rudimentary form of speech developed early on in our evolution. The conclusion comes from studies of fossilised skulls discovered in the mountains of Spain. A team of Spanish and US researchers used CT scans to measure the bones and spaces in the outer and middle ears of five specimens, thought to belong to Homo heidelbergensis. This species is thought to be a relative of the ancestral line leading to neanderthals. The team worked out how well the hearing apparatus they found could respond to sounds of various frequencies. The hominids' ears would have been sensitive to frequencies between two to four kilohertz, the range most important for understanding human speech. Chimpanzees' ears are relatively insensitive at those frequencies. Their ears are most strongly attuned to sounds peaking at either one kHz or eight kHz.

High sensitivity
But modern humans have evolved much sharper hearing in range suggested by the hominids' ears. The ancestral humans' sensitivity approached that of modern humans, suggesting that they too could distinguish the sounds of speech.
"Human hearing differs from that of chimpanzees and most other apes in maintaining a relatively high sensitivity from two kHz up to four kHz, a region that contains relevant acoustic information in spoken language," writes the team. "Our results show that the skeletal anatomy in these hominids is compatible with a human-like pattern of sound power transmission through the outer and middle ear at frequencies up to five kHz, suggesting that they already had auditory capacities similar to those of living humans in this frequency range," the researchers conclude.

Journal reference: Proceedings of the National Academy of Sciences (DOI: 10.1073/pnas.0403595101)

Bob Holmes and Shaoni Bhattacharya,

 

Family words came first for early humans

09:30 26 July 04
Exclusive from New Scientist Print Edition.

One of a Neanderthal baby's first words was probably "papa", concludes one of the most comprehensive attempts to date to make out what the first human language was like. Many of the estimated 6000 languages now spoken share common words and meanings, notably for kin names like "mama" and "papa". That has led some linguists to suggest that these words have been carried through from humans' original proto-language, spoken at least 50,000 years ago. But without information on exactly how often these words occur across distantly related languages, there has been little evidence to support that claim. What is more, some words of similar sound and meaning, such as the English "day" and the Spanish "dia", are known to have arisen independently. Now Pierre Bancel and Alain Matthey de l'Etang from the Association for the Study of Linguistics and Prehistoric Anthropology in Paris have found that the word "papa" is present in almost 700 of the 1000 languages for which they have complete data on words for close family members.

Common ancestry
Those languages come from all the 14 or so major language families. And the meaning of "papa" is remarkably consistent: in 71 per cent of cases it means father or a male relative on the father's side. "There is only one explanation for the consistent meaning of the word 'papa': a common ancestry," Bancel says. He presented the findings at the Origins of Language and Psychosis conference in Oxford, UK, in July 2004. But debate over whether modern languages carry the remnants of the language spoken at the dawn of humanity is likely to continue. Don Ringe, a linguist at the University of Pennsylvania in Philadelphia, says that babies may simply associate the first sound they can make with the first people they see - their parents. That, too, would lead to words like "papa" acquiring similar meaning in many languages. Even Bancel admits that there will never be conclusive proof. "We have no Neanderthals around to ask."

 Anna Gosline,

 

Protección contra el síndrome alcohólico fetal

by Catherine Zandonella  

Journal reference: Proceedings of the National Academy of Sciences (DOI: 10.1073/pnas.1331636100)

A drug to protect unborn babies from the harm caused their mother's excessive drinking is a step closer, with the discovery of a specific way to block alcohol's toxicity. Fetal Alcohol Syndrome (FAS) is the leading preventable cause of mental retardation in children in the US, affecting up to three babies in every 1000 births. While stopping drinking is the most obvious solution, alcoholic mothers can find this very difficult - motivational programs have historically only been about 30 per cent effective. A protective drug remains some years away, but the latest research shows how the fetal brain could specifically be shielded from alcohol. Michael Charness at Harvard Medical School and his colleagues found that a protein fragment called NAP stops alcohol from thwarting neurons' ability to connect to each other during brain development. Earlier work by the team found that alcohol interferes with L1, a protein that allows neurons to stick to one another . Also, scientists at the US National Institutes of Health have showed that NAP could abolish FAS in mice.

Side effects
But it was unclear whether NAP specifically blocked alcohol's neurotoxicity, or resulted from NAP's known ability to protect against neurological insults. Determining which was the case was important, as the more precise the action of a drug, the fewer side effects are likely to be seen.
But teasing out the anti-alcohol effect from the overall neuroprotective effect required some complex lab work, involving the creation of a series of slightly different NAP variants. Charness and colleagues then tested these and found one compound that protected mouse embryos in culture from ethanol but offered no protection against another neurotoxin called tetrodotoxin. This showed that NAP blocks specifically blocks ethanol toxicity. Furthermore, only a very small amount of NAP was needed for protection, again meaning fewer side effects.

Magic bullet
Mary Velasquez, a behavioural researcher at the University of Texas-Houston Health Sciences Center, says a drug would certainly be welcome among women at risk of FAS. "All the clients I see are looking for a magic bullet," she said.
But she expressed reservations about any treatment that would allow a woman to keep drinking throughout pregnancy because of the numerous other social and health-related effects of alcohol. Some recent studies have reported that even light drinking may cause decreased attention span, poor motor skills and poor emotional development in babies. But the UK agency Alcohol Concern advises that drinking one or two units once or twice a week is very unlikely to cause harm. Journal reference: Proceedings of the National Academy of Sciences (DOI: 10.1073/pnas.1331636100)

 

Web links:
Fetal Alcohol Syndrome, CDC
Fetal Alcohol Syndrome, UK
US National Institute on Alcohol Abuse and Alcoholism
Alcohol Concern, UK
Proceedings of the National Academy of Sciences

Catherine Zandonella
From New Scientist Online News 22:00 09 June 03

 

El DNA mitocondrial puede ser heredado por vía materna y paterna

17:01 23 August 02
NewScientist.com news service
Artículo original disponible en PDF : New England Journal of Medicine (vol 347, p576)

Mitochondria may not be inherited solely through the maternal line, according to new research that promises to overturn accepted biological wisdom. If confirmed by other researchers, the findings could have huge implications for evolutionary biology and biochemistry. Robert Sanders Williams, from Duke University Medical Center in North Carolina, says the findings are "remarkable and unanticipated. This is more than a mere curiosity. It asserts the principle that it can occur in humans. It could have significant implications for the study of human evolution and the migrations of populations," he says.

For decades biologists have assumed that mitochondria - the cells' power stations - are inherited solely through the maternal line. Mitochondria in the sperm from the father were presumed to be destroyed immediately after conception, leaving behind only those from the mother. But Marianne Schwartz and John Vissing from the University Hospital Rigshospitalet in Copenhagen, have discovered that one of their patients inherited the majority of his mitochondria from his father. "Even with very sensitive methods, paternal mitochondrial DNA has never been detected in man before," Schwartz told Reuters. "There are many examples of family pedigrees that follow mitochondrial diseases through the maternal line."

New England Journal of Medicine (vol 347, p576)

Little oxygen
The pair made the discovery while trying to discover why one of their patients suffered extreme fatigue during exercise. The 28-year-old man had an entirely normal heart and lungs and his muscles appeared healthy. But on closer inspection, Schwartz and Vissing discovered that his muscles absorbed very little oxygen.
This led them to examine the genetic sequence of his mitochondria. They discovered two mutations in his mitochondrial DNA - one of which was responsible for his extreme fatigue. To try and investigate the mutations further, they also sequenced the DNA of his mother, father and uncle. To their surprise, the sequence matched those of his father and uncle.

Spontaneous mutation

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Muscle biopsies showed that about 90 per cent of his mitochondria came from his father. However, the mitochondria in his blood, hair roots and fibroblasts came entirely from his mother. The two mutations appear to have arisen spontaneously during, or shortly after, conception.

The researchers think inheritance of paternal mitochondrial DNA is probably very rare. But the findings will have implications for a number of branches of biology. Evolutionary biologists often date the divergence of species by the differences in genetic sequences in mitochondrial DNA. Even if paternal DNA is inherited very rarely, it could invalidate many of their findings. It will also have implications for scientists investigating inherited metabolic diseases.

Danny Penman

Journal reference: New England Journal of Medicine (vol 347, p576)

 

La Academia de Medicina de Gran Bretaña realizó Reunión Científica sobre Evolución y Enfermedad (ver detalle en PDF)

 
Participantes:  Professors Bill Bynum, Richard Dawkins, Mel Greaves, Randolph Nesse, Steven Sterns, Steve Austad, S Boyd Eaton, David Weatherall, Robin Weiss and Lewis Wolpert.

Dietary change was a driving force in human evolution

By William R. Leonard Scientific American November 13, 2002 (versión PDF)

We walk on two legs, carry around enormous brains and have colonized every corner of the globe. Anthropologists and biologists have long sought to understand how our lineage came to differ so profoundly from the primate norm in these ways, and over the years all manner of hypotheses aimed at explaining each of these oddities have been put forth. But a growing body of evidence indicates that these miscellaneous quirks of humanity in fact have a common thread: they are largely the result of natural selection acting to maximize dietary quality and foraging efficiency. Changes in food availability over time, it seems, strongly influenced our hominid ancestors. Thus, in an evolutionary sense, we are very much what we ate.

Frequent sex reduces pregnancy complications

09:40 25 November 02
 TEMA DE LA ASIGNATURA RELACIONADO CON ESTA NOTICIA: Sesión teórica Adaptación:Proceso y Producto

Low fertility and frequent pregnancy complications may be the price that humans have paid for evolving a large brain. For the fetus to get enough nutrients to grow a hefty brain the placenta has to aggressively invade a mother's uterus, says a new theory. But that can also provoke her immune system, causing dangerous complications. However, recent research suggests that exposure to a man's semen helps a women's immune system prepare for pregnancy (New Scientist print edition, 9 February, p 32). So low rates of conception in humans reduce complications during pregnancy by giving a woman's immune system more time to adapt. Human fetuses spend 60 per cent of their energy on their brain, three times as much as other mammals. Twenty weeks into pregnancy, the placenta attacks the uterine wall for a second time, burrowing in more deeply than in any other mammal. But burrowing deeper is risky. It can provoke the mother's immune system to attack the placenta, which is loaded with foreign genes from the father. This can trigger pre-eclampsia, where the placenta leaks toxins into the mother's circulation, causing blood pressure to spike dangerously. Within hours it can escalate into kidney failure, brain haemorrhaging and death.
Try and try again
It is thought that humans are the only mammals to suffer frequent pre-eclampsia, which occurs in three per cent of pregnancies. We are also far less fertile: a bitch that mates just once when it is on heat usually gets pregnant, yet women typically take six months to conceive.
Research by Pierre-Yves Robillard, a neonatologist at Sud Réunion Hospital on the Indian Ocean island of Réunion, has shown that women who have sex with the father for over a year before getting pregnant have a five per cent chance of developing high blood pressure and pre-eclampsia compared with a massive 40 per cent chance for those who have only been having sex with the father for four months or less. Robillard is now proposing that this is why we are less fertile - the extra sex gives women a better chance of surviving the placental invasion. "If we had kept the same fertility as other mammals, we would have pre-eclampsia rates of 20 per cent," he told a workshop about pre-eclampsia in Mauritius. "Humans could not have survived."

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Better care
The theory has generated both interest and scepticism. "It's an interesting idea that placental invasiveness has something to do with brain expansion," says David Haig, an evolutionary biologist at Harvard University, "but other possibilities can't be eliminated."

For example, pre-eclampsia may have become more common as societies became better at caring for ailing mothers and babies.

And Robert Martin, an anthropologist at The Field Museum in Chicago, questions whether invasive placentas are linked to larger brains. "Dolphins have a non-invasive placenta, yet the next biggest brain sizes after humans are found in dolphins," he says.

Douglas Fox - NEW SCIENTIST ON-LINE EDITION

Adelantos evolutivos en salud

Eaton SB, Strassman BI, Nesse RM, Neel JV, Ewald PW, Williams GC, Weder AB, Eaton SB 3rd, Lindeberg S, Konner MJ, Mysterud I, Cordain L. Department of Anthropology, Emory University, 2887 Howell Mill Road NW, Atlanta, GA 30327, USA. daphne@mindspring.com

Prev Med 2002 Feb;34(2):109-18

Health promotion's promise is enormous, but its potential is, as yet, unmatched by accomplishment. Life expectancy increases track more closely with economic prosperity and sanitary engineering than with strictly medical advances. Notable achievements in the past century--the decreased incidences of epidemic infections, dental caries, and stomach cancer--are owed to virologists, dentists, and (probably) refrigeration more than to physicians. Prevention speaks against tobacco abuse with a single voice, but in many other areas contradictory research findings have generated skepticism and even indifference among the general public for whom recommendations are targeted. Health promotion's shortcomings may reflect lack of an overall conceptual framework, a deficiency that might be corrected by adopting evolutionary premises: (1) The human genome was selected in past environments far different from those of the present. (2) Cultural evolution now proceeds too rapidly for genetic accommodation--resulting in dissociation between our genes and our lives. (3) This mismatch between biology and lifestyle fosters development of degenerative diseases. These principles could inform a research agenda and, ultimately, public policy: (1) Better characterize differences between ancient and modern life patterns. (2) Identify which of these affect the development of disease. (3) Integrate epidemiological, mechanistic, and genetic data with evolutionary principles to create an overarching formulation upon which to base persuasive, consistent, and effective recommendations. Copyright 2001 American Health Foundation and Elsevier Science (USA).

Evolutionary health promotion: a consideration of common counterarguments.

Eaton SB, Cordain L, Lindeberg S. Departments of Anthropology and Radiology, Emory University, 2887 Howell Mill Road NW, Atlanta, GA 30327, USA. sboydeaton@mindspring.com

Prev Med 2002 Feb;34(2):119-23

The proposal that Late Paleolithic (50,000-10,000 BP) ancestral experience might serve as a model for prevention research and even, if justified by experiment, as a paradigm for health promotion recommendations is sometimes discounted, before critical assessment, because of reservations based on unjustified preconceptions. Most often such biases involve comparative life expectancy, potential genetic change since agriculture, the heterogeneity of ancestral environments, and/or innate human adaptability. This paper examines these topics and attempts to show that none of them justifies a priori dismissal of the evolutionary approach to preventive medicine. Evolutionary health promotion may ultimately be invalidated because of its falsification by experiment or because another theory accords better with known facts, but these commonly held prejudices should not forestall its thoughtful consideration and investigative evaluation. Copyright 2001 American Health Foundation and Elsevier Science (USA)

Selección natural en poblaciones humanas detectada con uso de SNPs

Tema de la asignatura relacionado con estas noticias: Sesiones teóricas "Selección Natural" y "Conceptos de especie y subespecie. Su aplicación a las poblaciones humanas"

PC Sabeti (...)  ES Lander, 2002. Detecting recent positive selection in the human genome from haplotype structure, NATURE |VOL 419 | 24 OCTOBER 2002 (texto PDF)

The ability to detect recent natural selection in the human population would have profound implications for the study of human history and for medicine. Here, we introduce a framework for detecting the genetic imprint of recent positive selection by analysing long-range haplotypes in human populations. We first identify haplotypes at a locus of interest (core haplotypes). We then assess the age of each core haplotype by the decay of its association to alleles at various distances from the locus, as measured by extended haplotype homozygosity (EHH). Core haplotypes that have unusually high EHH and a high population frequency indicate the presence of a mutation that rose to prominence in the human gene pool faster than expected under 

¿Y, entonces, cuál es la diferencia?

Tema de la asignatura relacionado con estas noticias: Sesión teórica "Evolución biológica y cultural"

W Enard, P Khaitovich, J Klose, S Zollner F Heissig P Giavalisco. K Nieselt-Struwe E Muchmore A Varki, R Ravid GM. Doxiadis RE Bontrop S Paabo, 2002. Intra- and Interspecific Variation in Primate Gene Expression Patterns  SCIENCE 296,  340 (texto PDF)

Although humans and their closest evolutionary relatives, the chimpanzees, are 98.7% identical in their genomic DNA sequences, they differ in many morphological,behavioral, and cognitive aspects. The underlying genetic basis of many of these differences may be altered gene expression. We have compared the transcriptome in blood leukocytes, liver, and brain of humans, chimpanzees, orangutans, and macaques using microarrays, as well as protein expression patterns of humans and chimpanzees using two-dimensional gel electrophoresis. We also studied three mouse species that are approximately as related to each other as are humans, chimpanzees, and orangutans. We identified speciesspecific gene expression patterns indicating that changes in protein and gene expression have been particularly pronounced in the human brain.

MF Teaford and PS. Ungar, 2000. Diet and the evolution of the earliest human ancestors, PNAS  97: 13506–13511 (texto PDF)

Over the past decade, discussions of the evolution of the earliest human ancestors have focused on the locomotion of the australopithecines. Recent discoveries in a broad range of disciplines have raised important questions about the influence of ecological factors in early human evolution. Here we trace the cranial and dental traits of the early australopithecines through time, to show that between 4.4 million and 2.3 million years ago, the dietary capabilities of the earliest hominids changed dramatically, leaving them well suited for life in a variety of habitats and able to cope with significant changes in resource availability associated with long-term and short-term climatic fluctuations.

Ontogenia virtual 11:35 23 August 02/Exclusive from New Scientist Print Edition

Temas de la asignatura relacionados con esta noticia: Sesión teórica "Curvas de crecimiento ontogénico en antropoides"

Virtual creatures, with muscles, senses and primitive nervous systems, have been "grown" from artificial embryos in a computer simulation. The multi-celled organisms could be the first step towards using artificial evolution to create intelligent life from scratch. Each creature begins life as a single "embryo" cell, containing a string of random numbers that represent its genome. Some genes tell the cell to split in two, forming a joint between the two new cells. Others tell it to develop different kinds of ability to make the organism move within or sense its virtual environment. Given a particular genome, each embryo cell will develop in a predetermined way. For example, it could develop cells with the ability to move the joints they are attached to, forming a virtual limb. Or they could develop sensitivity to light or touch. Give the embryo a different genome and it will develop into a different cell arrangement. In a parallel with real cells, the virtual embryos contain simulated chemicals that switch its genes on or off. When the simulation is run, genes activated by the "chemicals" make the cell act in different ways. And some of the virtual genes produce chemicals that activate other genes. Josh Bongard, an AI researcher at the University of Zurich, ran the simulation until each cell had grown into a creature of up to 50 cells. He then tested each one to see how well it pushed a simulated box. By setting one creature against another, Bongard was soon able to find which cells grew into the most effective "pushing" creatures.

Temas de la asignatura relacionados con esta noticia: Sesión teórica "Filogenias moleculares de antropoides. El organismo humano como antropoide neoténico"

Molecular analysis of Neanderthal DNA from the northern Caucasus, Igor V. Ovchinnikov, Galina P. Romanovak, Vitaliy M. Kharitonov, Kerstin Lidenß & William Goodwin NATURE VOL 404: 490, 30 MARCH 2000 (texto PDF)

Enlace con los orígenes del ser humano

Temas de la asignatura relacionados con esta noticia: Sesión teórica "Fósiles de homínidos"

Artículos sobre los hallazgos obtenidos en el estudio de los orígenes de nuestros ancestros homínidos, publicados en la revista Nature el 11 de Julio de 2002 (enlace al sitio web)

-Leakey, L. S. B. A new fossil skull from Olduvai. Nature 184, 491–493 (1959) (texto PDF)
Comentario: Fossil-hunter Louis Leakey had been scouring East Africa for clues about human origins in vain for 30 years before he (or rather, his wife) hit the jackpot at Olduvai Gorge in Tanzania. The new player on the fossil scene was lantern-jawed 'Nutcracker man'
-Leakey, L. S. B., Tobias, P. V. and Napier, J. R. A new species of the genus Homo from Olduvai Gorge.
Nature 202, 7–9 (1964) (texto PDF)
Comentario: Leakey scores again with fossils associated with primitive tools. He announces Homo habilis — 'handy man' — the first fossil member of our own genus; and with him, the first stirrings of technology

-Johanson, D. C. and Taieb, M. Plio-Pleistocene hominid discoveries in Hadar, Ethiopia. Nature 260, 293–297 (1976) (texto PDF)
Comentario: Donald Johanson pushes the human story back beyond the 3-million-year-mark with a skeleton, later assigned to Australopithecus afarensis. The skeleton is now known as 'Lucy', after Lucy in the Sky with Diamonds, the Beatles' tune popular in the field camp
-Leakey, M. D. and Hay, R. L. Pliocene footprints in the Laetolil Beds at Laetoli, northern Tanzania. Nature 278, 317–323 (1979) (texto PDF)
Comentario: When a volcanic eruption sent a rain of ash over what is now Tanzania, an adult and child, probably both Australopithecus afarensis, set out to watch the show — leaving, as a poignant souvenir, perfect and very modern-looking footprints, preserved in the ashfall

-A new hominid from the Upper Miocene of Chad, Central Africa. MICHEL BRUNET (...)  CHRISTOPH ZOLLIKOFER. Nature 418, 145–151 (2002) (texto PDF)

El bajo peso al nacer altera la ovulación durante la adolescencia

Temas de la asignatura relacionados con esta noticia: Seminario Mortalidad neonatos. Práctico 1

14:25 06 August 02
NewScientist.com news service. Emma Young. This story is from NewScientist.com's news service

Low birth weight disrupts ovulation in teenage girls and might affect fertility in later life, say Spanish researchers. They think it could account for some cases of unexplained infertility in women - about one in six couples who cannot conceive is given this diagnosis. A team led by Lourdes Ibáñez at the Hospital Sant Joan de Deéu in Barcelona studied 49 girls who were an average of 15 and a half years old. Twenty-four were classed as having a low birthweight - about 2.3 kilograms, compared with a normal average of 3.3 kg. Regular blood tests over a three-month period revealed that only 60 per cent per of the low birthweight girls were ovulating, compared with 96 per cent of the normal group, regardless of the teenagers' size and weight. Journal of Clinical Endocrinology and Metabolism (vol 87, p 3391) (Obtener versión PDF de este artículo)

 

El ser humano aún está evolucionando

Temas de la asignatura relacionados con esta noticia: Sesión teórica "Selección natural"

13:07 24 April 01
 NewScientist.com news service. Joanna Marchant. This story is from NewScientist.com's news service

Humans are still evolving, according to new research that contradicts the prevailing view that modern society's healthcare and technology means human populations are not changing genetically. In particular, the scientists say that, in industrialised societies, behavioural traits that cause women to have children earlier are becoming more common. Ian Owens from Imperial College in London and his colleagues used data about the lives of 2710 female twins in Australia to calculate the evolutionary "fitness" of each woman - a measure of the number of descendants her lineage would leave. Cultural factors such as religion and education had a big impact on fitness, but they could not explain everything. "If you remove everything that's cultural, there's still an enormous difference between women," says Owens. He estimates that while 50 to 60% of fitness is environmentally determined, 40 to 50% of it is genetic. Evolution (vol 55 p 423)(Obtener versión PDF de este artículo)

 

 

 

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